So after messing around with this a lot, I managed to get it working. There was a ton wrong, highlighted in bold below (I don't know how to bold things that are in CODE tags). I ended up using a second set of passthrough shaders because it was easier to set what I wanted. Basically I was missing vertexAttribPointer calls that I thought were bound to the buffer before.

Hi, I am working on tessellation with transform feedback these days too. But right now, I still can not get it working. In my code, I use tessellation shader to generate a sphere object from a single input vertex, this works fine. Then I want to obtain the vertices and normals of the sphere generated by the tessellation via transform feedback. Right now, all I get in the transform feedback buffer is the input vertex without tessellation. Do you have any idea, what is wrong? Thanks in advance. Sorry for my poor English. Here is my tessellation shader:
vertex shader: